Puff puff....

So late this morning I started my car, allowed it to warm up for 2-3 minutes while I gathered my stuff for work (it's like 100 degrees outside, I wanna be nice to the motor) and when I pull away, I see a small puff of smoke waft by my passenger window. It looked whitish. I stopped and watched the exhaust for about a minute, and everytime time the radiator fans would kick on a bit of smoke would find its way out of the tailpipe, but would dissipate shortly thereafter. Also once I had driven it for about 5 minutes it would no longer do it.

I checked a few basic things. The car runs great, considering the heat. Pulls hard as ever, doesn't stutter or stumble under throttle. It doesn't overheat. I even left it idling for about 15 mins while I ran into the restaurant where I work just to see. Coolant and oil level are good, and the oil on the dipstick looks healthy, at least. I've got the car on ramps in the garage while it cools off and I'm about to change the oil. I'm at about 3100 miles since my last one anyway. I'm pretty religious about keeping the oil changed.

I called Neal from SOG (directly...on his cell phone per his suggestion), and we spoke about it for a little while. In short he thinks I shouldn't be worried. He described a similar occurence with a 2004 wrx he had that a similar setup to mine (Stage 2) with a FMIC setup as well. He said it would smoke when idling occasionally but it never caused any real issues. He even suggested I open it up a little the next time I'm on the highway (since I really haven't in awhile when I thought about it). He said just to watch oil consumption and my temp gauge, and as long as those are fine it shouldn't be a real problem. He's seen "lots of healthy cars do pretty much the same stuff."

I searched nasioc briefly and came up with possible issues: turbo seals, valve seals, or at worst a head gasket, but if the oil is clean I imagine that last one is unlikely. I've also heard about some STIs that had this sort of problem. They would smoke screen on startup but it was apparently not a major problem and didn't need to be worried about.

Vitals on the car in question:
2008 WRX (2.5L)
Cobb Stage 2 Reflash
Full Catless 3" exhaust
K&N Drop in Air filter

33,000 miles.

Anyway, any insight would be appreciated. Apologies for the length

 

mine does it too. I thought it was oil and after driving around all day (playfully) I put a quart of oil in it since it had been awhile since my last oil change and surely had burned off plenty. Well the next morning I checked the oil before I started the car up and it was way over so I had King suck some out.

I'm thinking its something up with the turbo, Every now and then I'll smell burning oil and white smoke will escape out of my hoodscoop. Upon inspaction the smoke is coming from below the turbo.

Other than occasionally a cloud of smoke I have not noticed any malfunctions in the car so far.

 

yup had the same thing with mine last Summer. As long as it's not blue smoke, or large plumes of white smoke you're good

 

Thanks a lot guys. Oil looked good, albeit a bit black. Nothing that shouldn't be there though. I'll keep an eye on it.

In the meantime, bump for peace of mind.

 

I guess you learn something everyday. I always thought letting it get out of open loop before driving it was optimal, but I guess that would make sense in this weather. Thanks Matt!

I appreciate you guys helping me out with my REX.

 

Since your catless your more likely to see it...I have noticed the samething at times

 

Just dont get into it before your up to temp

 

agreed

 

:roflwtf:

On a side note...I see it occasionally, comes out from the hood scoop or around the turbo/dp area. Spooked me the first time.

 

:eek3: hecalleditarex!

 

Agreed for now. But if it does get worse, worry.

WHAT.

WHAT.

WHAT.



Main technical info turn on!!



So heres what happens during a startup condition on ANY modern piston internal combustion engine, only relating to the oiling system and other important info.

1. Starter turns engine over.
1a. There is enough oil pump rotor speed to start oil moving thru the sump/pump/oil filter and galleys during this action, 100~300 RPM.
2. Ignition, engine gets to target 'cold' RPM, 700~1500 RPM.
2a. Galleys are at full pressure. Bearings have full pressure.

The above process takes less than 1 second in most cases. Only longer if the starting process is longer.

At this point you want to wait until full operating temperature to 'beat' on it, meaning higher load states, high RPM, etc etc...easy driving and lower RPM is fine.


The real engine damage comes from two things here:

1. Beating on it when cold.
2. Oil changes.*


*During an oil change the pan is emptied and the filter is changed.

During the pan drain the sump is also emptied.

During the filter change, the main galley is emptied as well. Also, unless you prefil the oil filter, the filter is dry.

Now the engine is started with a 1/2 filled sump (partially refilled when you put oil in thru the filler), an empty filter and a mostly empty main galley.

Once the engine gets to idle RPM, the pump rotors can displace enough to draw the air/oil mix into the pump and force that thru the engine. In a matter of milliseconds (ms) it'll get a pure oil suppy. But we're talking in the range of 200~500ms here.

Oh wait, what about all that air in the main galley and the oil filter? Where does it go?

Well, thru the system. The pump sends a wall of oil in the displace the AIR thats in the filter and main galley. Now you have a wall of air infront of the oil. This air displaces any oil in front of it before the real pressurized oil gets there.

Thus you have a moment of true oil starvation every time you start the engine AFTER performing said oil change w/out prefilling the filter.

This whole process lasts around 1.5~3 seconds total.

To lessen that to 1/2 or less of the above time, prefill the oil filter until its saturated and it cannot accept any more oil. Be careful installing it, you may drip some oil.


Now back to the warmup....

Its ALWAYS good to let your engine run for a few minutes after initial startup to allow the engine, the oil and the coolant to start to approach operational temperatures. This will lengthen the life of your engine.

If you've got a neighborhood road that has a slow speed limit, 5~20mph, that can be your 'warm up'.


/WJM's technical rant.

 

Good stuff WJM!

 

maybe I am just being strange here, but burning fluids coming out of my car is a concern.... that shit is meant to stay IN the engine

 

Excellent point.

However, the situation that icallitarex is describing is pretty much impossible to diagnose w/out having the car in person.

The new engine in my WRX/now in my wife's WRX has never smoked. Previous engine in wife's WRX smoked from time to time. Neither consumed oil or coolant at any noticeable level.

I've also seen many a WRX/STi/LGT/FXT smoke on occasion with same results.

*shrug*

 

See I was thinking the same thing...that smoke or the burning of fluids can never be considered normal. Upon talking to Neal and discovering that he's seen lots of healthy cars come through with the same symtpoms, and also from the number of people here and elsewhere who have experienced the same thing with no real accompanying problems I've decided to just keep my eye on it for now. The car doesn't consume an abnormal or even noticeable amount of oil or coolant. The oil also looked fine and dandy coming out. My coolant is about halfway between "full" and "low" (a little toward low maybe but nothing alarming) but I'm planning on flushing it and also replacing my transmission fluid later this week or next anyway. I'm technically overdue for those two things...but thankfully not by much.

I appreciate everyone's help, and thank you Wil for the writeup. That thing about prefilling your filter is really random but I can totally see how it helps. I always do it now.


Keep the posts coming! Learning new stuff is always a plus for me.

 

If memory serves me correctly some manufacturers allow up a quart of oil burned per 1000 miles. I know this is not exactly related but it say how supposedly "normal" some things are that you would think are a problem.

 

it's coming from somewhere, it may just not be noticeable. leak is small enough to not be a concern

on a sidenote, just fixed my house AC. bad starting capacitor. suck it cobb HVAC you assholes. cost me $15